Apparatus for heat setting yarn



July 1, 1959 E. J. SERFASS ETAL 2,896,060

APPARATUS FOR HEAT SETTING YARN Filed June 11, 1956 Z5 Sheets-Sheet 1 IN VEN TORS. EA EL JSA'RFASS.

r44 ATTORNEYS.

July 21, 1959 E. J. sERFAsS ET AL 2,895,050

APPARATUS FOR HEAT SETTING YARN Filed June 11, 1956 s Sheets-Sheet 2 HHT IN VEN TORS.

EA 11-1.. J SE/PF'ASS. y T/VALTERLZ IEA 01.55,

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July 21, 1959 ss A 2,896,060 APPARATUS FOR HEAT SETTING YARN Filed June 11, 1956 3 Sheets-Sheet 3 To OTHER MA CH/NES IN VEN TORS. EA IPL J 55/?!7455. MLTERD IPA DLE'E.

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Unite APPARATUS FOR HEAT SETTING YARN Application June 11, 1956, Serial No. 590,713 6 Claims. (Cl. 219-36) This invention relates to apparatus for heat setting yarn and more particularly for setting continuously moving yarn. The invention is especially useful in a continuous treatment of yarn for providing stretch yarn by high false twisting, heat setting, and detwisting a suitable yarn, such as nylon. Since the invention has .proven highly successful in the commercial production of stretch nylon yarn, this embodiment of the invention will be described by way of illustration. However, it should be understood that it is contemplated that the invention and certain features thereof may be usefully employed for other treatments of fibres and yarns.

In producing stretch yarn by the continuous method utilizing false twisters, it is of great importance to provide heat setting means which will not only subject continuously moving yarn to the proper setting temperature but which also meets other cost and operational require ments.

In practice several hundred to several thousand yarns are run simultaneously, and therefore the unit cost (a) of equipment and (b) of operation per yarn for supplying the, required temperature is an important factor. Additionally, in order to operate a number of machines, each handling a large number of yarns, it is of greatest importance that themeans for supplying heat to each yarn be capable of accurately maintaining the same degree of heat per yarn heating unit, i.e., the units must be of great uniformity. Otherwise the yarns will be subjected to different setting conditions, resulting in yarns which lack that degree of uniformity essential to production of high quality knitted articles or knitted fabrics. Furthermore, it is desirable that the temperature be substantially uniform throughout the heat setting zone of each individual yarn. In view of the speed at which yarn travels, a substantial temperature is required in the setting Zone.

In order to provide for successful operation, it is necessary that the temperature of the setting zones be accurately adjusted in accordance with the size of yarn being treated and the rate of speed of the yarn passing through the setting zone. Therefore, it is desirable to provide means for simultaneously adjusting the temperature of the heating zones for the several yarns and for maintaining the temperature uniform with respect to all yarns.

It is usual in throwing operations for one operator to handle apparatus comprising many hundreds of spindles, and therefore it is important to provide heat setting units which may be easily and quickly replaced and which are not subject to breakage or damage.

An object of this invention is to provide apparatus for filling the above requirements while avoiding objections inherent in apparatus heretofore used. More particularly it is an object of the invention to provide apparatus for heat setting a multiplicity of yarns wherein means is provided for simultaneously adjusting the temperature in the heating zones for all yarns and maintaining the temperature uniform for said multiplicity of yarns.

Another object is to provide apparatus of the character described in which the cost of the heat setting means and rates Patent the cost of supplying heat are low. Another object of the invention is to provide heater units so constructed and arranged as to facilitate rapid assembly in the apparatus and replacement in a simple manner. Another object of the invention is to provide an electrical heating unit capable of withstanding a setting temperature of about 600 F. in continuous operation and in which the heat loss is extremely low and the heat transfer to the yarn is extremely high. A further object of great importance is the provision of heater units so constructed and arranged that they present great uniformity as to heating characteristics not only throughout the length of individual heaters but as between a multiplicity of heaters.

The novel features of the invention are pointed out with particularly in the appended claims, and a more complete and detailed description of the invention will now be given in connection with the accompanying drawings, in which:

Fig. 1 is a side elevational view of an electrical heating unit with parts broken-away to show certain details;

Fig. 2 is a cross-sectional view taken at 22 of Fig. 1;

Fig. 3 is a side elevational view of a heating unit assembly comprising the heating unit of Fig. l and mounting and attaching means therefor;

Fig. 4 is an end elevation of the assembly shown in Fig. 3;

Fig. 5 is a somewhat schematic front elevational view showing one yarn-treating unit, representative of a large number of identical units comprised in a machine, in which the heating device of Fig. 1 provides the heat setting means;

Fig. 6 is a somewhat schematic view showing the arrangement of a large number of said heating units in a typical installation and electrical supply means therefor; and

Fig. 7 is a view similar to Fig. 5 showing a modification.

Referring to the drawings and more particularly to Figs. 1 and 2: an electrical heating unit made in accordance with our invention is designated in general as H and comprises an electrical heating element in the form of a "straight tubular member 1 made of suitable electric resistance material and providing therethrough an axial passage 2 through which the yarn being set may be passed without contact with the heated walls. The tube 1 is surrounded by a tubular electrical insulator 3 whose interior diameter is substantially larger than the exterior diameter of the tube 1 so as to provide an annular air chamber 4 serving as a heat insulator for the tube 1. The tubes 1 and 3 are held in concentrical and axial alignment by a pair of spaced apart end pieces such as 5 which are preferably cup-shaped, each having an end wall 6 and a cylindrical side wall 7 whose open end faces inwardly. The end walls 6 are provided with bores through which pass respectively opposite ends of the tube 1 which is rigidly secured to the end walls 6 in intimate electric contact therewith by suitable means such as silver solder 8 engaging the exterior wall of tube 1. To facilitate obtaining uniformity of resistance and to aid in manufacture the end wall 6 is slightly dished in the region surrounding the tube 1, and as a further aid to uniformity of reistance, the solder 8 is preferably used in the form of a solder ring. The opposite ends of the insulator tube 3 are telescopically disposed within the cylindrical side walls 7 of the end pieces 5 and the insulator tube 3 is of such diameter and length as to provide a slight clearance between the end pieces and the tube to permit sufiicient relative movement to accommodate differences in the coefficients of expansion of the tubes 1 and 3 when the tube 1 is heated to the desired temperature, i.e., to deliver up to approximately 600 F.

In order to obtain uniformity in temperature through the length of tube 1, it should be uniform as to size and wall thickness throughout its length, and in order to provide for uniformity of heat characteristics among a multitude of units, it isimportant that the tubes be substantially identical each with respect to the others: We have found that tubes which are made of a resistance alloy of the general character of 80% nickel, 14%, chrome and 6% iron may be produced with great uniformity and have given entirely satisfactory results. In apparatus which has been used in commercial production, entirely satisfactory results have been obtained by the use of the tube 1 having a -inch outside diameter, a wall thickness of 0151.001 inch and an over-all length of eight inches. Similarly, the insulator tube 3 in such apparatus is slightly less than one inch in diameter with a wall thickness of inch and the cylindrical walls 7 into which it fits have an inside diameter of one inch. For the tube 3 We preferably use a paper or other suitable fibrous shell impregnated with melamine or the like material. Such a tube has the advantages of good electrical insulating qualities, heat insulating qualities and great toughness and durability against breakage or distortion. While we have obtained the desired heat characteristics by the use of insulating tubes made of Pyrex, such tubes not only dispel considerable heat but become too hot to be conveniently handled and are subject to breakage. Therefore, from the standpoint of efiiciency in the saving of power consumption, convenience in handling, and the prevention of breakage, it is preferable that the tubes 3 be not only a good electrical insulator but a heat insulator, and of such nature as to resist breakage and distortion. The insulating tube 3 and the pieces 7 provide a suificient enclosure to furnish an air chamber surrounding the tubular member 1, and we have found that such an air chamber provides a most efiicient heat insulation, permitting the unit to be of a relatively small size and facilitating production ata substantially low cost.

Referring more particularly to Figs. 3 and 4: the electrical heater H is mounted and is electrically connected by means of U-shaped metal clips such as 9 in which the end pieces such as 5 are tightly engaged by spring action of the clips 9, and this spring action is preferably supplemented by auxiliary U-shaped clips such as 10. The clips 9-40 are made of suitable material such as beryllium copper and are rigidly mounted on an insulator panel 11 by suitable means such as screws 12 and nuts 13. The screws 12 serve as binding posts to which electrical conductors such as 14 may be secured by means of nuts such as 15, and the panel 11 serves as a convenient means of mounting the assembly on the machine frame with the tube 1 in accurate alignment with the yarn travel. The clips 9 are provided with inwardly extending arms such as 16 which are slightly spaced from the outer ends of the end pieces 5 so as to permit lengthwise expansion of the tube 1 when heated. While the end clips 9 and are sufiiciently stiff to assure proper contact, their gripping action is not such as to prevent sliding movement by the end pieces 5 during expansion of the heating tube 1.

Referring more particularly to Fig. 5, it will be seen that the thread-treating unit as a whole comprises means for supporting a pirn of yarn 20 from which the yarn such as 21 is fed through a suitable guide such as the pigtail 22, thence through a tensioning device 23, through a pigtail 24, through the heating unit H and through the hollow shaft of a false twister 25, through a traverse guide 26 on to a take-up spool 27 which is frictionally driven by a take-up roller 28. Except for the heating unit H, the several parts of the apparatus disclosed in this figure are more or less conventional. Machines adapted to twist a multiplicity of yarns are well-known as single-deck uptwisters and in one typical example one machine has eighty-eight spindles, and the like number of twisting units are mechanically driven by a common means such as a belt 29, and the take-up rollers 28 are driven by a common shaft. Such an arrangement is so well-known in conventional uptwisters as to need no further detailed description. In the operation of the apparatus of Fig. 5 the yarn passing between the tensioning device 23 and the twister is highly twisted, and in its highly twisted state the yarn is set by heat supplied by the heating unit H. As the yarn leaves the upper end of the twister 25, whose upper end is supplied with a twisting head 25a, the yarn is detwisted to thereby produce the well-known stretch yarn which is thereupon wound on the spool 27.

In one commercial embodiment of the invention, which is referred to by way of illustration, the twisters 25 were driven at a speed of about 20,500 r.p.m. and the yarn was moved in its path of travel by the take-up roller 28 at a linear speed of about 27 feet per minute. Under these conditions seventy-denier yarn was treated and set at a temperature within the range of about 465-467 F., the yarn being highly twisted to about seventy-five turns per. inch.

The optimum temperature for different sizes of yarn and for different speeds of travel will of course vary and in general the temperature range of heat setting may vary over a range of about 400-600 F. In cases where twisters having extremely high rotating speeds are employed, the yarn is fed at a correspondingly high linear speed through the twisters and in such cases it may be found desirable to utilize a plurality of heating units H.

In Fig. 7 there is shown an embodiment in which a plurality of heating units H are arranged in tandem in axial alignment with the yarn 21. In this embodiment, the false twisters 25' may conveniently take the form of the device disclosed in co-pending application of Phillip Boillat et al., Serial No. 407,725, filed February 2, 1954, which is electrically driven and in which the twister shaft is supported in air bearings and rotates at much higher speeds than is possible with the arrangement shown in Fig. 5. In this embodiment the heating units H are operated at the temperature referred to above in connection with Fig. 5, and therefore to accommodate the higher rate of speed of the yarn, three are used. This permits uniform tube length and current supply, etc.; but where space is a factor, it 'is to be understood that fewer tubes may be used by supplying more current to raise the temperature correspondingly.

Apparatus comprising a multiplicity of heating units and means for simultaneously adjusting them to the desired temperature and maintaining a uniform temperature will now be described With reference more particularly to Fig. 6 which somewhat schematically illustrates apparatus comprising several machines, each of which has eighty-eight spindles. Two of such machines are designated respectively as A and B and additional machines may be included as indicated. Each of said machines comprises a plurality of groups, such as I, II, of heating units H; the present embodiment having eight groups of eleven heating units each in each machine, but in order to simplify the drawing only groups I and II have been shown and the remaining six groups are indicated by a suitable legend. The heaters H of each group are connected in series to the output of respectively corresponding step-down transformers such as 30 which are connected in parallel in a circuit comprising voltage adjusting means 31 whereby the temperature may be adjusted to the desired degree in all of the heating units simultaneously for a given machine. In order to maintain a constant voltage in the supply line, suitable means is provided such as a voltage regulator 32, which is common to said plurality of machines. As a further means of maintaining uniform temperatures an automatic control unit 33 is utilized and operates under the control. of a resistance element 34, positioned in the vicinity of the heaters being controlled and serving as an ambient temperature sensitive resistance. By way of example, it is noted that successful resultsihave been obtained by employing as the voltage regulating unit32'a General Electric Model GE l-30548B Znductrol to vary'the input voltage and for the automatiecontrol 33 a Model GE 1-43277, also made by General Electric Company. This arrangement has been 'foundto maintain the voltage within very close limits of say two volts;

In the present embodiment of the invention the power line supplies 230 volts and a voltage reduction transformer such as 35 is provided for each machine having an output voltage of 115 volts suppliedtothe voltage regulating device 31, for which purpose we have successfully utilized a powerstatj In-the present embodiment the step-down transformers 30 are in the form of filament transformers having an output voltage of 6.3 volts. Current supplied thereby to each'group of heaters is approximately fourteen amperes and the voltage drop across each heater unit H is approximately .5 volt. From this it will be seen that the'power consumption per heater is only seven watts, which presents a very marked-improvement over heat setting units heretofore employed.

In order to accurately maintain the temperature Within the yarn passage 2 (Fig. l) of the heating units H at the desired temperature, a temperature sensing device is provided having a temperature sensitive element, such as a thermo-couple, disposed Within one of the heating units H; said temperature sensing device being designated in general as 36. In this way the temperature indicated by the sensing device 36 will be substantially identical with the temperatures in each of the multiplicities of the heating units H. While the temperature sensing device 36 of the present embodiment gives a visual indication of the temperature permitting manual adjustment of the voltage to furnish the desired temperature, it is contemplated that through means well-known in the electrical art, the voltage regulation may be eifected automatically under control of the temperature sensing device 36.

From the foregoing it will be understood that the present invention is useful not only in constructing new a paratus but in converting presently existing uptwisters for the throwing of stretch yarn and other yarns wherein it is desired to heat-set the fibres. In either case the common control means and heater arrangement in such apparatus presents greatly improved structural and operational advantages. Further meritorious features of our invention reside in the heating unit which will withstand delivering up to 600 F. setting temperature in continuous operation; which is insulated in such a manner as to provide maximum heat transfer to the yarn being set at a minimum heat loss to the surrounding atmosphere; which provides an axial, heated passage, permitting the yarn to travel through without touching any metallic surface; which is so constructed that a series may be conveniently connected electrically in such fashion as to simplify facilities for control of a multiplicity of heaters; which are capable of repeated installation and changeability without elaborate wire changes; which may be produced at substantiallylow cost and which is of such electrical uniformity that a single control mechanism may be utilized for a large number of heaters while maintaining uniform setting temperatures for a multiplicity of yarns.

While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appended claims to cover all such modifications.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Yarn setting apparatus comprising an electrical resistance heating tube having an axially extending bore and a wall of substantially uniform cross-sectional area throughout its length, an insulator tube of substantially greater internal diameter than the external diameter of said heating tube-surrounding s'aid-heatingt'ube, and means holding said tubes in substantial concentricspaced relationshipand bridging the spacebetween said 'tubes adjacent theirends to thereby provide'a closed annular air chamber-surrounding "said heating tube, said holding rneans'providing for relative movement between said'tubes to allow for the differences incoeflicients of expansion of said tubes.

2.;Yarn setting apparatus comprising an electrical resistance heating tube'having a substantially uniform wall thickness throughout its length and an axially extending bore, end pieces to which theside wall of said tube exterior is rigidly securedin intimate electrical contact adjacent its respectively opposite ends, and an insulator tube of substantially larger interior diameter thanthe exterior diam'eterof said resistance tube surrounding thesame and providing an annular insulating air space thereabout, said insulator tube "being held 'in positionradially' and longitudinally by said end pieces and interconnected heating tube while providing for movement between said end pieces and'said'in'sulato'r tube due-to longitudinal expansion and contraction of said resistance tube under temperature changes of about 500 F.

3. Yarn setting apparatus comprising a hollow cylindrical electric resistance tube having a substantially uniform relatively thin wall throughout its length, cupshaped end pieces provided with central bores in which the opposite ends of said tube are disposed and to which the exterior of said tube is rigidly secured in intimate electric contact, and an insulator tube of substantially larger interior diameter than the exterior diameter of said resistance tube surrounding said resistance tube and having its opposite ends in sliding telescopic engagement with said cup-shaped end pieces to thereby provide an annular heat-insulating air space between said resistance tube and said insulator tube, said insulator tube being supported by said end pieces for relative movement with respect thereto to provide for the difference in the coefiicients of expansion of said tubes at temperatures of about 500 F.

4. Yarn setting apparatus comprising an electric resistance heating tube having a uniform relatively thin wall throughout its length, two cup-shaped electrically conducting end pieces having end Walls provided with centrally disposed bores and substantially cylindrical side walls with their open ends facing toward each other and being of a diameter substantially greater than the diameter of said resistance tube, said resistance tube having its opposite ends disposed in said bores respectively and rigidly secured to said end walls in intimate electric contact therewith, an air-impervious insulator tube surrounding said resistance tube and having its opposite ends in sliding telescopic engagement with the cylindrical walls of said end pieces to thereby provide a concentric heat insulating air chamber around said resistance tube, said insulator tube being supported by said end pieces freely for relative limited movement with respect thereto to provide for the diflference in the coefficients of expansion of said tubes at temperature changes of about 500 F.

5. Yarn setting apparatus comprising a nickel-chrome alloy electric resistance heating tube about eight inches long and about outside diameter having a uniform wall thickness of about .015 inch throughout its length, two cup-shaped electrically conducting end pieces having end walls provided with centrally disposed bores and substantially cylindrical side walls with their open ends facing toward each other and being of an internal diameter of about one inch, said resistance tube having its opposite ends disposed in said bores respectively and soldered to said end walls, and a tube of melamine impregnated fibrous material having an outside diameter slightly less than the inside diameter of said cup-shaped end pieces and a wall thickness of the order of A inch, said tube surrounding said resistance tube and having its opposite ends in sliding telescopic engagement Within the cylindrical Walls of said end pieces to thereby provide a concentric heat insulating air chamber around said resistance tube, said insulating tube being supported by said end pieces freely for relative movement with respect thereto to provide for the difference in the coefficients of expansion of said tubes when said heating tube attains an internal temperature of about 500 F.

6. In apparatus of the character described, a heating unit assembly comprising an electric resistance tube having a substantially uniform relatively thin wall throughout its length, cup-shaped end pieces provided with central bores in which the opposite ends of said tube are disposed and to which said tube is rigidly secured in intimate electric contact, an insulator tube of substantially larger interior diameter than the exterior diameter of said resistance tube surrounding said resistance tube and having its opposite ends in supported engagement with said cup-shaped end pieces to thereby provide an annular heatinsulating air space between said resistance tube and said insulator tube, said insulator tube being supported by saidend pieces for relative movement with respect thereto to provide for the diflfere nce in the coeflicients of expansion of said tubes, 21 pair of generally U-shaped spring References Cited in the file of this patent UNITED STATES PATENTS 2,617,007

Atkins Nov. 4, 1952 2,803,109 Stoddard et al Aug. 20, 1957 FOREIGN PATENTS 1,091,308 France Oct. 27, 1954 745,337 Great Britain Feb. 22, 1956 

